#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
int main()
{
	int a = 0;
	int sum = 0;
	//for (a = 1; a <= 100; a++)
	for(a=3;a<=100;a+=3)
	{
		//if (a % 3 == 0)
		
			sum += a;
	}
	printf("%d", sum);
	//for (a = 1; a <= 10; a++)
	//{
		//printf("%d", a);
	//}j
	return 0;
}